Synthesis of 14beta hydroxysteroids

ABSTRACT

THERE IS PROVIDED A NOVEL METHOD OF INSERTING A 14BHYDROXY GROUP INTO STEROID NUCLEI UNSUBSTITUTED AT THAT POSITION AND IN PARTICULAR THERE IS PROVIDED A METHOD OF CONVERTING 3,22-DIHYDROXY-23,24-DINOR-5$-CHOLENES OR THE 3-ACYLATES THEREOF INTO THE CORRESPONDING 3, 14B,22-TRIHYDROXY-23,24-DINOR-5$-CHOLANES AND THE 3,22-DIACYLATES THEREOF. THIS METHOD ALSO PROVIDES A NOVEL AND SIMPLE MEANS OF SYNTHESIZING DIGITOXIGENIN.

United States Patent 3,828,029 SYNTHESIS OF 145 HYDROXYSTEROIDS Eliahu Caspi, 1 Ardmore Road, Worcester, Mass. 01609,

and Donald J. Aberhart, 1005 Perry St. NE., Washington, DC. 20017 No Drawing. Continuation-impart of abandoned application Ser. No. 262,395, June 13, 1972. This application Apr. 3, 1973, Ser. No. 347,597

Int. Cl. C07c 173/00 U.S Cl. 260-239.55 R I 14 Claims ABSTRACT OF THE DISCLOSURE There is provided a novel method of inserting a 1413- hydroxy group into steroid nuclei unsubstituted at that position and in particular there is provided a method of converting 3,22-dihydroxy-23,24-dinor-y-cholenes or the 3-acylates thereof into the corresponding 3, 14,3,22-trihydroxy-23,24-dinor-5f-cholanes and the 3,22-diacylates thereof. This method also provides a novel and simple means of synthesizing digitoxigenin.

RELATED APPLICATIONS This application is a continuation-in-part of copending application, Ser. No. 262,395, filed June 13, 1972, now abandoned.

FIELD OF THE INVENTION Synthesis of 14e-hydroxy steroids.

DESCRIPTION OF THE PRIOR ART The important cardiac active steroids possess a 14/3-hydroxy group and a ketopyran or ketofuran group at the 175-position of the steroid nucleus. All of these moieties are known to be sensitive to many reagents generally used in steroid synthesis and it has heretofore been difficult to produce compounds wherein both groups are present. The 14,8-hydroxy group has been found particularly difiicult to insert. A synthesis of digitoxigenin has been reported by Sondheimer et a1. (J.A.C.S. 84, 876 (1962); Tetrahedron, 22, 3189 (1966)). This synthesis starts from methyl 3B-acetoxy-l4 8-hydroxy-5j3-etianate which in turn was previously synthesized from 5/3-androstan-3/3-ol-17- one acetate in a 9-step sequence (Meyer, Helv. Chim. Acta., 29, 1580 (1946); and Ruzicka et al., ibid., 30, 1342 (1947) It was deemed desirable to find a simpler method of synthesis of digitoxigenin and related compounds than that referred to therein. Such synthetic route should start from cheap and readily available steroidal starting materials and be of fairly wide applicability.

SUMMARY OF THE INVENTION In the process of the present invention, there is utilized as starting material a 3,22-dihydroxy-23,24-dinor-5f-chol- 7-ene (III) suitably in the form of the 3-acyl ester. This starting material may be obtained from the corresponding 5-cholesta-7,22-diene 3-ester suitably the acetyl ester (1) which is subjected to selective oxidative cleavage of the C double bond to yield the corresponding 22-al (II) which in turn is reduced by means well known in the art to yield the starting material (III). The 3-acyloxy-22-hydroxy steroid (III) is treated with a phosphorus trihalide, suitably phosphorus tribromide to yield not the expected 22-bromide compound, but the totally unexpected 14,22- epoxide (IV). The epoxide may also be formed by treatment of steroid (HI) with other cyclizing agents such as hydrochloric acid and the like. This epoxide may be readily oxidized by suitable oxidizing agents to yield the corresponding 14,13,22-lactone (V). Where it is desired to form the corresponding 143,22-dihydroxy compound (VII), the lactone is reduced with a strong reducing agent.

Where it is desired to synthesize digitoxigenin, there is used as starting material, a 5B-ergosta-7,22-dien-3fl-acylate (a compound of Formula I), the lactone (V) is treated with a suitable Grignard reagent or an organometallic agent suitably an alkali metal aryl or alkyl to give the corresponding 1 tB-hydroxy-ZO-disubstituted methylene derivative (VI) which are then readily cleaved by ozonolysis to give the l4 8-hydroxy-20-oxo-pregnane-3-acylate, suitably the acetate, that is to say, the known 14B-hydroxy-20- oxo-Sfi-pregnane-Bil-acetate, which may then be converted into digitoxigenin by the method of Sondheimer et a1. (vide supra).

The invention described herein was made in the course of work under a grant or award from the Department of Health, Education, and Welfare.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the process of the present invention, the starting material, namely the 3,22-dihydroxy-23,24-dinor-5-chol-7- ene (III), suitably in the form of the 3-ester, is obtained from the corresponding 5-ergosta-7,22-diene 3-ester, by oxidative cleavage, and subsequent reduction of the aldehyde thus formed. Any readily available ester may be utilized and the invention is not to be considered limited therein. Among the suitable esters are those of alkanol acids, preferably C -C alkanol acids and arylalkanoic acids such as phenyland naphthyl alkanoic acids having 1-5 carbon atoms in the side chain, acetic and benzoic acids are especially preferred. In the preferred modification of this process, the 3-acyl-ergosta-diene is taken up in a suitable solvent such as hydrocarbon or halogenated hydrocarbon suitably methylene chloride or the like and ozonized suitably in the presence of a base, suitably an organic base such as pyridine, until ca. 1.5 equivalents of ozone have passed in. The reaction mixture is then worked up in the usual manner, suitably by quenching with methanol and dimethyl sulfide. The mixture is evaporated to dryness redissolved in an alkanol and saturated aqueous sodium bisulfite. The aqueous solution is extracted with ether and the ether discarded. The aqueous phase is made basic and re-extracted with ether to yield on work-up the corresponding 22-al (II). Alternatively the C double bond could be cleaved by other oxidative methods, for example, using potassium permanganate or osmium tetroxide, with periodic acid. The product may then be reduced to the corresponding 22-hydroxy compound (III).

In the preferred modification this reduction is carried out using a reducing agent such as metal hydrides, their alkoxy analogs or the like such as sodium borohydride, diborane, or the like. It is especially preferred to take up the aldehyde (H) in a mixture of methanol and methylene chloride and treat the same with a solution of sodium borohydride, suitably a 1 to 1.5 molar excess of hydride to yield, upon work-up, the desired compound (III).

The thus produced 3-acyloxy-22-hydroxy-23,24-dinor- 5g-chol-7-ene is taken up in a solvent, suitably a halohydrocarbon solvent, like methylene chloride, chloroform, carbontetrachloride, or the like, and treated with phosphorous trihalide suitably phosphorous tribromide.

Preferably, the reaction may be carried out at low temperatures, suitably from 0 C. to 30 C'., preferably at ambient temperatures for from about 1 to about 72 hours preferably for about 48 hours. The reaction mixture is not worked up in any way, but directly purified by chromatography, suitably thin layer chromatography to yield, upon recrystallization of the eluate, the 14,22- epoxy-23,24-dinor-5f-cholan-3-acylate (IV). Alternatively there may be used cyclizing agents such as thionyl halides, phosphorus oxyhalides, perhalic acids and certain Lewis acids, for example, thionyl chloride or bromide, phosphorus oxychloride, perchloric acid, hydrochloric acid or hydrobromie acid, boron trihalides or stannic chloride.

The 14,22-epoxide (IV) is then oxidized with a strong oxidizing agent. It is preferred to take -up the epoxide in a nonhydroxylic, polar, organic solvent suitably acetone or the like and treat it with an appropriate oxidizing agent, such as chromic acid, nickel tetroxide, ruthenium tetroxide, freshly prepared ruthenium tetroxide being especially preferred. This reaction can be carried out according to the method previously described by D. M. Piatak et al. (J. Org. Chem. 34, 116 (1969)).

The reaction mixture is purified by filtration suitably through a material such as celite, the filtrate reduced in volume, diluted with water, and extracted with a water immiscible solvent such as'ether to yield, upon evaporation of the ether, the corersponding 14,22-lactone (N) which may then be further purified as needed.

Where it is desired to synthesize digitoxigenin, the lactone, which in that case would be the 3,6-acyloxy-2-3, 24-dinor-5B-cholano-1419,22-lactone (V) is taken up in a suitable solvent, for example, a hydrocarbon solvent such as benzene, toluene or an ethereal solvent such as diethyl ether or tetrahydrofuran which had previously been dried by methods well known in the art. To the reaction mixture is added a slight excess suitably between 3 and 4 moles of an organometallic aryl or alkyl such as lithium butyl, or lithiumphenyl, or the like. While the corresponding Grignard reagents may also be used it has been found more convenient to use the lithium derivatives. The reaction mixture is stirred for from about minutes to about 2 hours. The reaction mixture may be heated under reflux, cooled, and the excess organometallic reagent destroyed and then worked up in the usual manner.

The residue is acylated, suitably acetylated then the acetates are dissolved in a suitable solvent such as benzene, and a small amount of acid, suitably p-toluene sulfonic acid is added and the mixture refluxed for 2-6 hours. After conventional work-up the thus produced 2Z-disubstituted-ZO-methylene steroid (V1) is isolated from the residue.

The methylene group may be cleaved by ozonolysis to yield the known 14,8-hydroxy-20dcetone (VHI) (Sondheimer, et al. Tetrahedron 22, 3189 (1966)). While selective ozonolysis is not required in this instance since merely the 22-olefinic group is to be cleaved, nevertheless, it is desirable to utilize mild reaction conditions.

The thus produced 3B-dihydroxy-ZO-oxo-Sfl-pregnane-3- acylate may then be converted into digitoxigenin in accordance with the procedure set forth in Sondheimer et al., I.A.C.S., 84, 875, (1962).

It should be noted that the process of the present invention appears to be dependent on a number of stereochemical factors. It has been found, for example, that where the steroid utilized is 22RS-hydroxy-5a-cholest- 7-en-3fi-ol, that is to say, that analog of Compound (V II) having an isopentyl moiety attached to the 22- carbon atom, no epoxide is formed but there is obtained a mixture of the corresponding A (IX) and A -22-hy- FIGURE 1 FIGURE 1.-'Continued II C Y CH OH K i 5:1 0 no (VII) hezeinabove R acetyl or C H CD- 3 -acetoxy-5B steroid acetoxy-5a steroid 3p-acetoxy-5a steroid gp-acetoxy-SB steroid an. COMPOUNDS 2 the corresponding the corresponding 3-HO-steroids BIQURE 2 (XII) RC i f (IV) a VIII 3b a la,

In a manner analogous to that set forth hereinabove, the starting point for the synthetic route using the corresponding A A and A steroids are the corresponding 5-ergosta-8(9)-, 8(14)-, and 14-22-dienes.

Thus, for example, 3-benzoyloxy-5g-ergosta-8(9), 22- diene is prepared either by the method of Hallsworth et al. (J. Chem. Soc., 1969, (1957)) or by the method of Barton et al. (J. Chem. Soc., 1771 (1949)). This ergosta diene (XV) is then oxidized by controlled cleavage to yield the aldehyde (XVI) corresponding to the aldehyde (II) in the A series. This controlled cleavage may be carried out in a similar manner utilizing as cleavage agents potassium permanganate or osmium tetroxide, in the presence of periodic acid, or by ozonolysis, the latter being preferred.

The aldehyde (XVI) is then reduced using a suitable reducing agent which will not, however, reduce the ester group at the 3- position, for example, sodium borohydride, diborane, or the like may be utilized to yield the corresponding 22 hydroxy 23,24-dinor-5g-chol-8(9)-ene 3- ester (XVIII). The 22-hydroxy steroid (XVIII) is then taken up in a suitable solvent, for example, a halohydrocarbon solvent such as methylene chloride, chloroform, carbon tetrachloride or the like, preferably chloroform and treated with an epoxidizing agent, for example a protic acid, such as the Lewis acid, for example, boron trifiuoride, stannic chloride, or the like, or a phosphorus trihalide suitably phosphorus tribromide, phosphorus tribromide in chloroform being especially preferred. The reaction is carried out under the conditions described hereinabove for the transformation of the 22-hydroxy steroid (III) to yield, also in this case, the epoxide (IV).

Similarly, 5 -ergost-8( 14),22-diene 3-esters (X) are pre pared in accordance with the method of Barton et al. (J. Chem. Soc., 1771 (1949)), Fieser and Fieser Steroids, Reinhold Publishing Company, 1959 (p. 114)). In the course of this synthesis, there is also prepared the corresponding 5-ergost-l4,22-diene 3-ester, which may be separated therefrom in the manner set forth in the cited reference.

The manner of proceeding to the epoxide (IV) from these materials is analogous to that set forth hereinabove starting with the 5-ergosta8(9), 22-diene 3-ester (XV), namely the dienes (IX) and (X) are subjected to oxidative cleavage to yield the 22-aldehydes (XI) and (XIII) respectively, which in turn are reduced to the corresponding 22-alcohols (XII) and (XIV). These are then subjected to epoxidation to yield the epoxide (IV) by subjecting them to the reagents set forth hereinabove in the manner set forth hereinabove.

The esters utilized herein are analogous to the esters utilized in the A sequence described hereinabove.

EXPERIMENTAL PROCEEDINGS Melting points are taken on a hot stage and are corrected. Specific rotations are determined for 12% solutions in chloroform. Silica gel Merck HF254+366 is used for thin layer chromatography (t.l.c.). Infrared spectra are determined as pressed disks in KBr on a Perkin-Elmer 237 instrument. UV. spectra are taken in methanol solution on a Perkin-Elmer 202 instrument. N.m.r. spectra are determined on a Varian HA-60 instrument operating at 60 mHz., using CDCl as solvent, unless otherwise stated. Chemical shifts are quoted in 6 (ppm) relative to an internal standard of tetramethyl silane. Mass spectra are taken on a Varian M-66 instrument. In certain cases precise masses are determined on spectra obtained on a Varian M-66 instrument. High resolution mass spectra were obtained on the NIH facility operated by Arthur D. Little Co., Cambridge, Mass.

EXAMPLE I 3a-Acetoxy-22-hydroxy-23,24-dinor-5e-chol-7-ene (III)a A cooled (78) solution of 3a-acetoxy-5fl-ergosta-7, 22-diene (I)a (9.09 g.) in CH Cl (400 ml.) and pyridine (2.5 ml.) is treated with 0 (1.5 equivalents) which is passed in at a rate of 42.5 mg. 0 per min. (determined iodometrically). Methanol (5 ml.) and dimethylsulfide (5 ml.) are added, and the solution allowed to warm to room temperature. The mixture is then evaporated to dryness in a stream of nitrogen.

The residue is dissolved in methanol ml.), and treated with 50 ml. of saturated aqueous sodium hydrogen sulfite. After shaking for 10 min., the viscous mixture is extracted with 4X 250 ml. ether, centrifuging after each extraction 5 min. at 500 rpm. The ether extract is dried and5 evaporated to yield mainly recovered starting material Then the aqueous phase is neutralized with aqueous sodium hydroxide, and treated with 20 ml. of saturated sodium carbonate. The solution is extracted with 4x 250 ml. ether, centrifuging as before. The ether extract is dried over sodium sulfate and evaporated. The major product is isolated by prep. t.l.c. (system 10% ethyl acetate-hexane; (R 0.5)) giving 2.07 g. of the aldehyde (II)a, which is recrystallized from MeOH, m.p. -92, [a] +74 (c., 2.22), v 2680, 1730, 1720, 1255, 1125 cm. n.m.r. bands at 0.61 (18-Me), 0.88 (19-Me), 1.15 (3H, d, I-6 c.p.s., 21-Mc), 2.0 (OAc), 4.72 (E, m, 3/8-H), 5.13 (1H, m, vinylic), 9.57 (111, d, J--3 c.p.s., CHO); extraneous peaks at 3.42 and 0.57 indicated an impurity. The mass spectrum has peaks at m/e 312 (MCH CO H), 297 (M-(CH CO H+CH 284 and 269.

The aldehyde (II)a (1.92 g.) is then dissolved in chloroform (25 ml.) and methanol (25 ml.) and treated with sodium borohydride (300 mg.) at room temperature for 1 hour. Ammonium chloride (1 g.) in H 0 ml.) is

added, and the mixture is extracted with chlorofrom. The

chloroform extract is dried, evaporated, and the crude product separated by prep. t.l.c. (25% ethyl acetate-hexane). The major product, R, 0.5), 1.25 g. is isolated and recrystallized from chloroform-methanol in prisms, to yield 30: acetoxy-22-hydroxy-23,24-dinor-5B-chol-7-ene (III)a, m.p. 132-133, [M +83; u 3560, 3400 (br), 1720, 1250 cm.- n.m.r. bands at 0.57 (18-Me), 0.87 (19-Me), 1.05 (3H, d, J=6 c.p.s., 21-Me), 1.62 (1H, D 0 exchangeable, l' 1.99 (OAc), 3.53 (2H, m, C 0H), 4.68 (1H, m, 3,B-H), 5.25 (1H, m, vinylic). The mass spectrum gives a low intensity peak at m/e 374 (M+, C H O and peaks at 314 (base peak, MCH3CO2H) and 299 (MCH CO H-CH In accordance with the above procedure, but starting with 3a-acetoxy-5-ergosta-7,22-diene (I)b, Bra-acetoxy- 5a-ergosta-7,22-diene (-I)c, 3B acetoxy-Sfl-ergosta-ZZZ- diene (I)d in place of 30: acetoxy 5B ergosta-7,22- diene (I)a, there is obtained the corresponding Fla-acetoxy-22-hydroxy 23,24 dinor-5a-chol-7-ene (HI)b,3,6- acetoxy-22-hydroxy 23,24 dinor-5a-chol-7-ene (HI)c, 3p aeetoxy-22-hydroxy-23,24-dinor-5 3-chol-7-ene (III)d. Similarly, but using the 3-benzoyloxy derivative in place of the 3-acetoxy derivative there is obtained the corresponding 3-benzoyloxy derivative.

I: accordance with the above procedure but starting wit 3a-acetoxy-5a-ergosta-8 (9 ,22-diene 3u-acetoxy-5fl-ergosta-8 (9) ,22-diene 3 fl-acetoxy-S u-ergosta-8 9 ,22-diene 3 B-acetoxy-5 B-ergosta-S 9 ,22-diene 3a-acetoxy-5a-ergosta-8 14) ,22-diene 3a-acetoxy-5 3-ergosta-8(14),22-diene 3 fl-acetoxy-S a-ergosta-8 14) ,22-diene 3 fl-acetoxy5 fl-ergosta-8( 14) ,22-diene 3a-acetoxy-5a-ergosta-14,22-diene 3 u-acetoxy-5,8-ergosta-14,22-diene 3 B-acetoxy-S a-ergosta- 14,22-diene 3 fl-acetoxy-S ,8-ergosta-14,22-diene instead of 3a-acetoxy-5B-ergosta-7,22diene I(a), there is obtained, respectively, the corresponding:

3a-acetoxy-22-hydroxy-23,24-dinor-5 8-chol-8 (9 ene 3 a-acetoxy-22-hydroxy-23 ,24-dinor- 5 5- chol- 8 (9) ene 318-acetoxy-Z2-hydroxy-23,24-dinor-5a-chol-8 (9 ene 3 fl-acetoxy-22-hydroxy-23,24-dinor-5 ,B-chol-S 9) ene 3oacetoxy-22-hydroxy-23,24-dinor5 z-cho1-8( 14 )-ene 3 aacetoxy-22-hydroxy-23 ,24-dinor-5 B-chol-8( 14) ene 3 fi-acetoxy-22-hydr0Xy-23,24-dinor-5 oc-ChOl-S 14) ene 3p-acetoxy-22-hydroxy-23,24-dinor-5B-chol-8( 14 ene 3a-acetoxy-22-hydroxy-23,24-dinor-5a-chol-14-ene 3 a-acetoxy-22-hydroxy-23,24-dinor-5fi-chol-14-ene 3 ,6-acetoxy-22-hydroxy-23,24-dinor-5 a-chol- 14-ene 3 B-acetoxy-22-hydroxy-23,24-dinor-5 B-chol- 14-ene Similarly, but using the 3-benzoyloxy derivative in place of 3-acetoxy derivative, there is obtained the corresponding 3-benzoyloxy derivative.

EXAMPLE II .3a-Acetoxy-14,22-epoxy-23,24-dinor-5 8-cholane (IV)a A solution of 0.0845 ml. phosphorus tribromide in 50 ml. chloroform is prepared. To 36 ml. of this solution is added 705 mg. of 3a-acetoxy-22-hydroxy-23,24-dinor 5,6-chol-7-ene (III)a and the mixture is kept at room temperature for 48 hours. The solution is washed with sodium bicarbonate, dried over sodium sulfate and evaporated. The crude product is purified by preparative t.l.c., giving 530 mg. of 31x acetoxy-14,22-epoxy-23,24-dinor-5 3-cholane (IV) a, recrystallized from methanol as prisms, mp. 139- 141, [011 -9 (0., 2.00), v 1725, 1230, 1220, 1010 cm.- n.m.r. bands at 0.68 (3H, a, 1:6 c.p.s., 21-Me) 0.92 (IQ-Me), 1.02 (18-Me), 2.03 (A0); part of an ABX pattern (2H) between 3.0 and 3.83, with J -=11!) c.p.s., J =1LO c.p.s. and J =6.0 c.p.s.; 4.72 (1H, m, Sfl-H). The mass spectrum exhibits intense peaks at m/e 374.2813 (M calcd. for C H O (374.2821) and m/e 359 (base peak).

In accordance with the above procedure but starting with:

3a-acetoxy-22hydroxy-23 ,24-dinor-m-chol-8 (9 )-ene .3 u-acetoxy-22-hydroxy-23,24-dinor-55-chol-8 (9 )-ene 3;8acetoxy-2-hydroxy-23,24-diuor-5u-chol-8 (9) ene 3 fl-acetoXy-22-hydroxy-23,24-dinor-5 ,8-chol-8 (9 )-ene 3a-acetoxy-22hydroxy23,24-dinor-5a-chol-8 14) ene 3a-acetoxy-22-hydroxy-23,24-dinor-5B-chol-8( 14) ene 3 B-acetoxy-ZZ-hydroxy-Z3,24-dinor-5 oc-ChOl-8 14 )-ene 3 ,3-acetoxy-22-hydroxy-23,24-dinor-5 p-chol-8 14) ene 3 a-acetoxy-22-hydroxy-23,24-dinor-5a-chol-14-ene 3u-acetoxy-22-hydroxy-23,24-dinor-5fl-chol-14-ene 3 fl-acctoxy-22-hydroxy-23,24-dinor-5 a-chol-14-ene 3 fi-acetoxy-ZZ-hydroxy-Z? ,24-dinor-5f3-chol- 1 4-ene in place of 3a-acetoxy-22-hydroxy-23,24-dinor-5fi-chol-7- ene, there is obtained, respectively, the corresponding 3a-acetoxy-14,22-epoxy-23,24-dinor-5a-cholane 3a-acetoxy-14,22-epoxy-23,24-dinor-5 3-cholane 3 fi-acetoxy-14,22-epoxy-23,24-dinor-5 e-cholane 3 B-acetoxy- 14,22-ep oxy-23 ,24-dinor-5fl-cholane 3a-acetoxy-l4,22-epoxy-23,24-dinor-5a-cholane 3a-acetoxy-14,22-epoxy-23,24-dinor-5fl-cholane 3 fl-acetoxy-14,22-epoxy-23,24-clinor-5a-cholane 3 p-acetoxy-14,22-epoxy-23,24-dinor-5 {B-cholane 3oz-acetoxy-14,22-epoxy-23,24-dinor-5u-cholane 3a-acetoxy-14,22-epoxy-23,24-dinor-5B-cholane 3 fi-acetoxy-14,22-epoxy-23,24-dinor-5 tat-cholane 3B-acetoxy-14,22-epoxy-23,24-dinor-S s-cholane Similarly, but using the 3-benzoyloxy derivative in place of the B-acetoxy derivative, there is obtained the corresponding 3-benzoyloxy derivative.

8 EXAMPLE nr A solution of 0.0845 ml. phosphorus tribromide in 50 ml. chloroform is prepared. To 36 ml. of this solution is added 705 mg. of 3 3-acetoxy-22-hydroxy-23,24-dinor,'55- chol-7-ene (III)d and the mixture is kept at room temperature for 48 hours. The solution is washed with sodium bicarbonate, dried sodium sulfate and evaporated. The crude product is purified by preparative t.l.c. giving 35-acetoxy- 14,22-epoxy, 23,24-dinor-5fi-cholane (IV)d which is recrystallized from methanol.

In accordance with the above product but where, in place of phosphorus tribromide there is used anhydrous hydrogen chloride, perchloric acid or thionyl chloride is obtained the same product.

EXAMPLE IV 3fi-Benzoyloxy-14,22-epoxy-23,24-dinor-5wcholane- IV) 0' 3fi-Benzoyloxy-Z2-hydroxy 23,24-dinor-5u-chol 7-enc (III)c' (79 mg.) is treated with 3.15 mg. (1 equiv.) of a solution of 0.0181 ml. phosphorus tribromidein 10 mg. chloroform, at room temperature for 18 hours. The solution is directly separated, without preliminary workup, by prep. t.l.c. (20% ethyl acetate-hexane; R 0.7) giving 318- :benzoyloxy-14,22epoxy-23,24-dinor-5a cholane (IV)c' (52.5 mg.) which is recrystallized from chloroformmethanol, needles, mp. -191, [u] 27 (c., 1.7 1), 11 1715, 1480, 1450, 1275, 1115, 710 crnr g n.m.r. bands at 0.68 (3H, d, J=6 c.-p.-s., 21-Me). 0.88 (19-Me), 103 (18-Me), 4.91 (1H, m, Zia-H); part of an ABX pattern (2H) appears between 5 3.12 and 3.83 with calculated J =6.5 c.p.s., J ='11.0 c.p.s., and J =11.0 c.p.s. The mass spectrum exhibits major peaks at m/e 436 -(M+, C2g'H40O3), 421 (base peak), 314 (MC H CO H). Anal. Calcd. for C H O C, 79.75; H, 9.25. Found C, 79.75; H, 8.85.

EXAMPLE V 3a-Benzoyloxy-14,22-epoxy 23,24-dinor-5a-cholane- (IV)b' Zia-B enzoyloxy-22-hydroxy-23,24-dinor-5a-chol 7 ene (1H)b (79 mg.) is treated with 3.15 ml. (1 equiv.) of a solution of 0.0181 ml. phosphorus tribromide in 10 ml. chloroform, at room temperature for 18 hours. The solution is directly separated, without preliminary workup, by prep. t.l.c. (20% ethyl acetate-hexane) giving 3abenzoyloxy-l4,22-epoxy-23,24-dinor-5a cholane (IV)b' (52.5 mg.) which is recrystallized from chloroformmethanol.

EXAMPLE VI 3u-Acetoxy-23,24-dinor-5p-cholano-22 14-lactone (V)a The SB-epoxide ('IV)a (210 mg.) is stirred at room temperature with 40 mg. ruthenium dioxide and sodium periodate (1.0 g.) in 15 ml. water and '30 ml. acetone for 18 hours. The mixture is diluted with water and extracted with ether. The ether extract is washed with water, sat. sodium chloride, dried (Na SO and evaporated. The lactone 'is purified by preparative t.l.c. (10% ethyl acetate-hexane; R, 0.3) giving 184 mg. of 3a-acetoxy- 23,24-dinor-5/3-cholano 22- 14 lactone (V) a, recrystallized from methanol, m.p. 179-181, [M 36" (c. 3.05), v 1725, 1720, 1230, 1130, 1015, 975 cmjn.m.r. bands at 0.97 (19-Me), 1.07 (IS-Me), 1.23 (3H, d, I-7 c.p.s., 21-Me), 2.03 (0A0), 290 (1H, :11, C-20 H), 4.68 (1H, m, 3 3-H). The mass spectrum exhibits a peak for the molecular ion at m/e 388.2602 (M calcd. for C H O (388.2613)), and low intensity peaks at m/e 360 (M"CO), 344 (M-CO2), 328 (MCH CO H). Intense fragments appear at m/e 292 (MC H O), and m/e 284 (M-(CH CO H+CO 9 EXAMPLE v11 3B-Acetoxy-23,24-dinor-5p-cholano-22 14-lactone (V)d The Sfl-epoxide (lV)d (210 mg.) is stirred at room temperature with 40 mg. ruthenium dioxide and sodium periodate (1.0 g.) in 15 ml. water and 30 ml. acetone for 18 hours. The mixture is diluted with water and extracted with ether. The ether extract is washed wih water, sat. sodium chloride, dried (Na SO and evaporated. The lactone is purified by preparative t.l.c. (10% ethyl acetate-hexane), giving 3;3-acetoxy-23,-24-dinor-5/3- cholano-22 l4-lactone (V)d, recrystallized from meth anol.

EXAMPLE VIII 3 3-Benzoyloxy-23,24-dinor-5B-cholano-22 l t-lactone- (V) c' Ruthenium dioxide (5 mg.) in acetone (2 ml.) is treated with sodium periodate (22 mg.) dissolved in acetone-water (1:1, 2 ml.). The yellow solution is added -to epoxide IV)c' (25 mg.) in acetone (2 ml.) and the mixture is stirred at room temperature. As the solution turns black, a solution sodium periodate (100 mg.) in acetone-water (1:1, 1 ml.) is added in portions over 3 hours. After -a total of 5 hours, i-propanol (2 ml.) is added, and stirring continued for 1 hour. The mixture is filtered through Celite, evaporated to half volume, diluted with water, and extracted with ether. The extract is washed with water, dried and evaporated.

The product is purified by prep. t.l.c. ethyl acetate-hexane; R 0.15), giving 3/3-benzoyloxy23, 2 4 dinor-Sfl-cholano 22+ 14 lactone (V)c' recrystallised from chloroform-methanol, prisms, mg). mp. 227 232, [a] +12 (c., 1.96), v 1720, 1275 cmf n.m.r. bands at 0.93 (l9-Me), 1.10 (18-Me), 1.27 (3H, d, I-6 c.p.s., 21-Me), 2.97 (1H, m, C-20-H), 4.93 (1H, m, 3a-H). The mass spectrum has peaks at m/e 450.2783 (M+, calcd. for C H O 450.2770), 422.2815 (M-CO; calcd. for C H O 423.2821), 406.2873 (MCO calcd. for C23H3go2 (M- csHgo, baS6 peak), 328 (MC H CO H).

EXAMPLE IX 3a-Benzoyloxy-Z3,24-dinor-5a-cholano-22 1'4-lactone Ruthenium dioxide (5 mg.) in acetone (2 ml.) is treated with sodium periodate (22 mg.) dissolved in acetonewater (1:1, 2 ml.). The yellow solution is added to epoxide (IV)b mg.) in acetone (2 ml.) and the mixture stirred at room temperature. As the solution turns black, a solution of sodium periodate (100 mg.) in acetone-water (1:1. 1 ml.) is added in portions over 3 hours. After a total of 5 hours, i-propanol (2 ml.) is added, and stirring continued for 1 hour. The mixture is filtered through Celite, evaporated to half volume, diluted with water, and extracted with ether. The extract is washed with water, dried and evaporated. The product is purified by prep. t.l.c. (10% ethyl acetate/hexane) to yield, upon crystallization from chloroform/ methanol 3w benzoyloxy-23,24-dinor-5a-cholano-22- 14-lactons (V) b.

EXAMPLE X 3a,14,8,22-trihydroxy-23,24-dinor-5fi-cholane (VI-I)a Lactone (V)a (68 mg.) in ether (50 ml.) is treated with lithium aluminum hydride (500 mg.) at reflux for 24 hours. The excess hydride is destroyed with ethyl acetate, then water is added dropwise until a white granular precipitate is formed. This is filtered and washed with ether. The combined ether solution is dried over Na SO and evaporated. The product 3a,14p,22-trihydroxy-23,24-dinor-5B-cholane (VII)a", 60 mg. is recrystallized from ethyl acetate to m.p. l95197 (needles), [a] +18 (c., 1.74), n.m.r. (DMSO d bands at 0.85 (19-Me), 0.93 (IS-Me), ca. 0.93 (21-Me, under 10 18-Me signal), 3.25 (1H, m, Sgt-H), 3.35 (2H, D 0 exchangeable, OH), 3.92 (1H, D 0 exchangeable, OH), 4.38 (2H, m, C-22-H2). The mass spectrum exhibits a low molecular ion peak at m/e 350 (C H O and major peaks at m/e 338 (MH O), 317

314 (M2H O), 299 (M--(2H O+CH 274 a 6 2 273 (M(C3H7O+H2O)), 255 (MC3H7O+2H2O))- EXAMPLE XI 3,8,145,22-trihydroxy-23,24-dinor-5 8-cholane (VIII)d Lactone (V)d (68 mg.) in ether (50 ml.) is treated with lithium aluminum hydride (500 mg.) at reflux for 24 hours. The excess hydride is destroyed with ethyl acetate, then water is added dropwise until a white granular precipitate is formed. This is filtered and washed with ether. The combined ether solution is dried over Na SO and evaporated. The product is recrystallized from ethyl acetate to yield 3B,14p,22-trihydroxy-23,24- dinor-SB-cholane (VII)d".

EXAMPLE XI'I 3a,145,22-trihydroxy-23,24-dinor-5u-cholane (VII)b" Lactone (V)b (68 mg.) in ether (50 ml.) is treated with lithium aluminum hydride (500 mg.) at reflux for 24 hours. The excess hydride is destroyed with ethyl acetate, then water is added dropwise until a white granular precipitate is formed. This is filtered and washed with ether. The combined ether solution is dried over Na SO and evaporated. The product is recrystallized from ethyl acetate to yield 3u,145,22-trihydroxy-23,24- dinor-5a-cholane (VII)b".

EXAMPLE XIII 3B,145,22-trihydroxy-23,24-dinor-5ot-cholane (VII)c" Lactone (V)c' (68 mg.) in ether (50 ml.) is treated with lithium aluminum hydride (500 mg.) at reflux for 24 hours. The excess hydride is destroyed with ethyl acetate then water is added dropwise until a white granular precipitate is formed. This is filtered and washed with ether. The combined ether solution is dried over sodium sulfate and evaporated. The product is recrystallized from ethyl acetate to yield 35,1413,22-trihydroxy-23,24-dinor- 5a-cholane (V'II)c".

EXAMPLE XIV 3p-Acetoxy-14fi-hydroxy-23 ,24-dinor-22-diphenyl- SB-chol-ZO-ene (VI) d Lactone (V)d (68 mg.) in ether (50 ml.) is treated with phenyl lithium (500 mg.) at ambient temperature followed by reflux for 2-8 hrs. The reaction mixture is worked up in the usual manner to yield an ether solution. The ether solution is dried over sodium sulfate and evaporated, and the residue acetylated in the usual manner. The obtained acetate is dissolved in benzene, several crystals of p-toluenesulfonic acid are added and the mixture refluxed for 2-6 hrs. The solution is washed and taken to dryness to yield BB-acetoxy-14 8-hydroxy-23,24-dinor- 22-diphenyl-5fi-chol-20-ene (VI )d.

In accordance with the foregoing procedure but using butyl lithium in place of phenyl lithium there is obtained the 3fl-acetoxy-14fi-hydroxy 23,24 dinor-22-dibutyl-5;8- chol-20-ene (VI)d.

EXAMPLE XV 3B-Acetoxy-14/3-hydroxy-20-oxo-5 3-pregnane (VIII)d 3,6-Acetoxy-145 hydroxy 23,24 dinor-22-diphenyl- 5/8-ch0l-22-ene (VI)d (213 mg.) in methylene chloride ml.) are treated at 78 with ozone.

Water is added and the mixture is shaken for 2-16 hrs. at room temperature. The organic phase is washed with sat. sodium chloride, dried over sodium sulfate, and

evaporated. The major product 3fl-acetoxy-14B-hydroxy- 20-oxo-5fl-pregnane is isolated by preparative t.l.c. (20% ethyl acetate-hexane), and is recrystallized from methanol mp. 150-151, +25 (OHCl v 1727, 1697 cm.-

In accordance with the foregoing procedure but starting with BB-acetoxy-l4fi-hydroxy-22-dibutyl-5p-pregn-20 ene, there is obtained the same product.

EXAMPLE XVI 3 fi-Benzoyloxy-22-hydroxy-23 ,24-dinor-5 a-chol- 8(9)-ene (XVII)c A cooled (78) solution of 3fi-benzoyloxy-5a-ergosta- 8(9), 22-diene(XV)'c (9.09 g.) in methylene chloride (400 ml.) and pyridine (2.5 ml.) is treated with ozone (1.5 equivalents) which is passed in at a rate of 42.5 mg. ozone per min. (determined iodometrically). Methanol (5 m1.) and dimethylsulfide (5 ml.) are added, and the solution allowed to warm to room temperature. The mixture is then evaporated to dryness in a stream nitrogen.

The residue is dissolved in methanol (80 m1.) and treated with 50 ml. of saturated aqueous sodium hydrogen sulfite. After shaking for 10 min., the viscous mixture is extracted with 4X 250 ml. ether, centrifuging after each extraction 5 min. at 500 r.p.m. The ether extract is dried and evaporated to yield mainly recovered starting material (3.5 g.).

Then the aqueous phase is neutralized with aqueous sodium hydroxide, and treated with 20 ml. of saturated sodium carbonate. The solution is extracted with 4X 250 ml. ether, centrifuging as before. The ether extract is dried over sodium sulfate and evaporated. The aldehyde (XVI) is isolated by preparative thin layer chromatography.

The aldehyde (XVI) (1.92 g.) is then dissolved in chloroform (25 ml.) and methanol (25 ml.) and treated with sodium borohydride (300 mg.) at room temperature for 1 hour. Work-up in the usual manner gives the desired 35-benzoyloxy-22-hydroxy 23,24 diIlOI-Sct-CIIOI- 8(9)-ene (XVII) c', which is recrystallized from chloroform-methanol.

EXAMPLE XVII 3fi-Benzoyloxy-14,22-epoxy-23,24-dinor-5u-cholane (IV)c from (XVII)c' 3,8 Benzoyloxy-22-hydroXy-23,24-dinor-5a-chol-8 (9)- ene (XVII)c' (79 mg.) is treated with 3.15 ml. of a solution of 0.0181 ml. phosphorus tribromide in 10 ml. chloroform at room temperature for 18 hours. Work-up as in Example IV gave 3fl-benzoyloxy-14,22-epoxy-23,24- dinor-5a-cholane (IV)c identical with that prepared from (III)c.

EXAMPLE XVIII 3 fl-Benzoyloxy-22-hydroxy-23,24-dinor-5a-chol-8( 14) -ene (XIV) c The 3fl'benzoyloxy 5a-ergosta-8(14),22-diene (X)e' is ozonized and processed as described in Example XVI to yield the corresponding 33 benzoyloxy 22 aldehyde (XIH). The aldehyde (XIII)c' is dissolved in chloroformmethanol and reduced in accordance with the method of Example XVI to yield 3fl-benzoyloxy-22-hydroxy-23, 24-dinor-5a-chol-8(14)-ene (XIV)c'.

EXAMPLE XIX 3fl-Benzoyloxy-14,22-epoxy 23,24-dinor-5a-cholane (IV)c from (XIV)c 35 Benzoyloxy-22-hydroxy-23,24-dinor-5a-chol-8 14)- ene (XIV)c (79 mg.) is treated with 3.15 ml. of a solution of 0.0181 ml. phosphorus tribromide in 10 ml. chloroform at room temperature for 18 hours. Work-up as in Example IV gave 3fi-benzoyloxy-14,22-epoxy-23,24-dinor- 12 Su-cholane (IV)c identical with that prepared from (III)c.

EXAMPLE XX 3 8-Benzoyloxy-22-hydroxy-22,23-dinor-5m-chol- 14-ene (XII)c' A solution of 3 3 benzoyloxy 5a-ergosta-14,22-diene (IX)c' is ozonized and then processed as described in Example XVI to yield the corresponding 3B-benzoyloxy- 22-aldehyde (XI). The aldehyde (XI) is dissolved in chloroform-methanol then reduced and processed as described in "Example XVI to yield the corresponding 35- benzoyloxy 22 hydroxy 23,24-dinor-5w-chol-14-ene (XII)c'.

EXAMPLE XXI 3 {i-Benzoyloxy- 14,22-epoxy-23 ,24-dinor-5 a-cholane- (IV)c from (XII)c' 3 B Benzoyloxy-22-hydroxy-23,24-dinor-5a-chol-14-ene (XII)c' (79 mg.) is treated with 3.15 ml. of a solution of 0.0181 ml. phosphorus tribromide in 10 ml. chloroform at room temperature for 18 hours. Work-up as in Example IV gave 3,3-benzoyloxy-14,22-epoxy-23,24-dinor- 5a-cholane (IV)c identical with that prepared from (III)c'.

EXAMPLE XXII In accordance with the procedures of Examples XVI through XXI, but where in place of 3B-benzoy1oXy-5uergosta-Q,22-dienes, where Q is 8(9), 8(14), or 14, there are utilized the corresponding 3a-benzoyloxy-5a-ergosta dienes, 3u-benzoyloxy-5fi-ergosta dienes, 3B-benzoyloxy- SIS-ergosta dienes, 3a-acetoxy-5a-ergosta dienes, 35-acetoXy-Sa-ergosta dienes, 3a-acetoxy-5fi-ergosta dienes, 319- acetoxy-SB-ergosta dienes or any of the other Sg -ergosta diene 3 g-esters defined hereinabove, there are obtained the corresponding 14,22 epoxy 23,24-dinor-5-cholane-3gesters (IV).

We claim:

1. In the process of synthesizing digitoxigenin the steps of sequentially reacting a 3-acyloxy-22-hydroxy-23,24- dinor-chol-Q-ene wherein Q is 7, 8, 8(14) or 14 with (a) an ether forming agent selected from the group consisting of hydrohalic acids, perchloric acids, thionyl halides and phosphorus trihalides and phosphorus oxyhalides.

(b) an oxidizing agent selected from the group consisting of chromic acid, nickel tetroxide, and ruthenium tetroxide (c) an alkyl or aryl organometallic compound selected from the group consisting of lithium alkyls, lithium aryls, alkyl magnesium halides, aryl magnesium halides, and magnesium, and

(d) ozone to yield the corresponding 3-acyloxy-14B-hydroxy-20-oxopregnane.

2. In the process according to Claim 1 utilizing as the ether forming agent, a phosphorus trihalide to yield the corresponding 3-acyloxy-14p-hydroxy-20-oxopregnane.

3. In the process according to Claim 1 the steps comprising reacting a 3-alkanoyloxy or 3-aralkanoyloxy-22- hydroxy-23,24-dinor-chol-Q-ene wherein Q is 7, 8, 8(14) or 14 with (a) phosphorus tribromide (b) ruthenium tetroxide (c) lithium butyl or lithium phenyl (d) ozone to yield the corresponding 3-alkanoyloxy or 3-aralkanoyloxy-l4 3-hydroxy-20-oxopregnane.

4. The steps of Claim 2 wherein Q is 7.

5. The steps of Claim 3 wherein Q is 7.

6. In the process of synthesizing digitoxigenin the steps of sequentially reacting a 3-acyloxy-22-hydroxy-23,24- dinorchol-Q-ene wherein Q is 7, 8, 8( 14) or 14 with (a) an ether forming agent selected from the group consisting of hydrohalic acids, perchloric acids,

13 thionyl halides and phosphorus trihalides and phosphorus oxyhalides, and

(b) an oxidizing agent selected from the group consisting of chromic acid, nickel tetroxide, and ruthenium tetroxide to yield the corresponding 3-acyloxy-23,24-dinor-cholano- 22 14-lactone.

7. In the process according to Claim 6 utilizing as the ether forming agent, a phosphorus 'trihalide to yield the corresponding 3-acyloxy-23,24-dinor-cholano-22- l4- lactone.

8. In the process according to Claim 7 the steps comprising reacting a 3-alkanoyloxy or aralkanoyloxy-ZZ- hydroxy-23,24-dinor-chol-Q-ene wherein Q is 7, 8, 8(14) or 14 with (a) phosphorus tribromide and (b) ruthenium tetroxide to yield the corresponding S-aikanoyloxy or 3-aralkanoyloxy-23,24-dinor-cholano-22 14-1actone.

9. In the process according to Claim 7 the steps comprising sequentially reacting a 3-acyloxy-22-hydroxy-23, 24-dinor-chol-ene with (a) a phosphorus trihalide, and

(b) an oxidizing agent selected from the group consisting of chromic acid, nickel tetroxide, and ruthenium tetroxide to yield the corresponding 3-acyloxy-23,24-dinor-cholano- 22 l4-lactone.

10. In the process according to Claim 8 the steps comprising sequentially reacting a 3 alkanoyloxy or 3- aralkanoyl-22-hydroxy-23,24-dinor-5p-chol-ene with (a) phosphorus tribromide,

(b) ruthenium tetroxide to yield the corresponding 3-a1kanoyloxy or S-aralkanoyloxy-23,24-dinor-cholano-22 14-lactone.

11. In the process of Claim 6 the step comprising reacting a 3 acyloxy 22 hydroxy-23,24-dinor-chol-7-ene with a phosphorus trihalide.

14 12. A compound of the general formula wherein R is alkanoyl or aralkanoyl, and R is H or =0.

13. A compound of the general formula wherein R is alkanoyl, or aralkanoyl, and R is alkyl, aralkyl, aryl or alkaryl.

14. A compound of the general formula 8 v 8 wherein R is alkanoyl, or aralkanoyl or hydrogen.

No references cited.

HENRY A. FRENCH, Primary Examiner US. Cl. X.R. 

